Downside: an individual who made an important discovery and patented her invention and licensed her technology to large companies would not be able to access her money for 17 years.
Where the _best_ of these will take fifty per cent as a fee?
Sounds a great deal.
I think what'd you'd actually see is specialist patent funding actuaries and patent evaluators making an interest rate bid dependent on the actual patent and inventor in question, much the way insurance industry works. The direct competition would be business loans, and maybe that'd be essentially what they were - secured business loans.
Lets say the USPTO uses Deep Learning to discover prior art and/or result disputes. A shorter time frame may be less risky for the inventor. After the escrow is released, there is no recourse for the licensee.